GW-501,516 (also known as GW1516 or GSK-516) is a drug developed by GlaxoSmithKline, which acts as a PPARδ modulator.[1][2] It activates AMP-activated protein kinase and stimulates glucose uptake in skeletal muscle tissue,[3] and has been demonstrated to reverse metabolic abnormalities in obese men with pre-diabetic metabolic syndrome, most likely by stimulating fatty acid oxidation.[4] It has been proposed as a potential treatment for obesity and related conditions,[5] especially when used in conjunction with a synergistic compound AICAR, as the combination has been shown to significantly increase exercise endurance in animal studies.[6][7]

Concerns were raised prior to the 2008 Beijing Olympics that GW-501,516 or the GW-501,516 / AICAR combination could be used by athletes as a performance enhancing drug which was not currently controlled by regulations or detected by standard tests. One of the main researchers from the study on enhanced endurance consequently developed a urine test to detect the drug, and made it available to the International Olympic Committee.[8] The World Anti-Doping Agency has also begun work on a test for the two drugs,[9] and they have been added to the prohibited list from 2009 onwards.[10]